文献类型：期刊文献

英文题名：Intermolecular photocyclizations of N-(ω-hydroxyalkyl)- tetrachlorophthalimide with alkenes leading to medium- and large-ring heterocycles-reaction modes and regio- and stereoselectivity of the 1,n-biradicals

作者：Shen, Yong-Miao[1,2]; Yang, Xiao-Liang[1]; Chen, Da-Qing[1]; Xue, Jie[1]; Zhu, Liang[1]; Fun, Hoong-Kun[3]; Hu, Hong-Wen[1]; Xu, Jian-Hua[1]

机构：[1] Institute of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China; [2] Institute of Chemistry and Chemical Engineering, Shaoxing University, Shaoxing 312000, China; [3] X-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, George Town 11800, Malaysia

年份：2010

卷号：16

期号：9

起止页码：2873

外文期刊名：Chemistry - A European Journal

收录：EI(收录号：20100812733565)、Scopus(收录号：2-s2.0-77149133384)

语种：英文

外文关键词：Atoms - Electron transitions - Free radical reactions - Nuclear magnetic resonance spectroscopy - Olefins - Photoreactivity - Regioselectivity

外文摘要：A new photocyclization strategy by using intermolecular tandem reactions between N-(ω-hydroxyalkyl)-4,5,6,7-tetrachlorophthalimides (1, 2, and 3) and a series of acyclic and cyclic alkenes is reported. Electron transfer of the triplet-excited phthalimide with the alkene and regioselective trapping of the alkene cation radical by the hydroxyl group at the phthalimide side chain gives a triplet 1,n-biradical, which after intersystem crossing (ISC) leads to regio- and diastereoselective synthesis of polycyclic heterocycles with an N,O-containing medium to large ring. Regio- and diastereoselectivity in the cyclizations are clarified by unambiguous steric structure assignments of the products by X-ray diffraction or extensive 2D NMR measurements. The diastereoselectivity is decided by the stereochemical course of the ISC process of the triplet 1,n-biradicals. These intermolecular photoreactions also furnish a new strategy to generate triplet 1,n-biradicals. Therefore, in photoreactions of 1 and 2 with phenylcyclohexene, the unprecedented stereoselective formation of products by intramolecular hydrogen-atom transfer in the 1,n-biradical intermediate was found (9 and 23). These facts provide direct verification to the reaction pathways of the 1,n-biradicals and give a new insight into the factors deciding reaction-pathway partitioning and stereoselectivity. ? 2010 Wiley-VCH Verlag GmbH & Co. KGaA.